How to (voltage drop) test a starter motor circuit

[@thomasldeanjr3337]

This is one of the best explanations of voltage drop in a starting system I've seen. Thank you so much!

[@billm5758]

Great video in telling you how to pinpoint the drop, not just a description of how it is occurring!

[@sandiegorestorations877]

Thank you for this video - I’ve watched about 10-15 different videos on this and this one was the most clear! You’ve helped me diagnose the issue with my project car!

[@beanercanned9021]

Hey my car has the same problem s wire only draws 0.2 volts

[@dortiz_dk3443]

Very educational for us getting ready for the A1 ASE Test! Thank you so much for making this video!

[@kville5796]

This is just up my street; very detailed and informative. Justin you're a star.

[@philgray1023]

If I had seen this during my apprenticeship I would not have become a nurse.

[@user-pf8tb9fu8x]

Why

[@jameswhitbread7173]

But your saving life's so perhaps that was your true calling. Anyway it's all going electric soon

[@davidfrench3657]

At least you don't have to buy tools to do your job now

[@matthewdubois6792]

@@jameswhitbread7173more likely getting turkey sandwiches and ginger ale while watching heart monitors.

[@871jamie]

You’re better off, being an auto tech you will eat a lot of bologna during the slow times.

[@stocks4bt]

Every teacher should use a setup like this one. Visual teaching & theory is better than just teaching theory

[@ndigs]

Especially when your dealing with AUTOMOTIVE issues...

[@milotorres6894]

Troubleshooting made simple explanation helps clear the air a b c no confusion spot on same page concepts...

[@Querencias7]

E X C E L L E N T demo, very nice setup too. Nice job indeed. Sharing your knowledge is greatly appreciated.

[@KamoheloPotsane]

Been watching other videos about voltage drop in a starter motor circuit and could understand jack! Here I am bumping into this well detailed and excellently demonstrated video by Mr. Miller, now I feel like an A+ student lol, thanks Mr. Miller, in the morning I'm definately going to check my car and try to diagnose where I could be losing voltage. Thanks a lot!

[@JustinMillerAutomotive]

Thanks for the feedback! I am glad it helped you. Good luck with the car.

[@milotorres6894]

Teaching not easy same sentiments automations workings can become fickled fiasco basics fuel fire ,and air needs eases rundown electrical most important...

[@brediaable]

I have had a lot of trouble understanding voltage drop concept it was really troublesom for me I have been to just about every web site there is well maybe not everey one but this guy (justin miller) is the best teacher, BEST VIDEO , best explanation, of voltage drop that there is on the web and his simulator might be the reason why I don,t know but after watching his you tube video a few times I thoroughly understand voltage drop which I thought I did before but I was mistaken. This guy is a BAD ASS TEACHER I don,t care hats off to you JUSTIN MILLER THANKS A LOT

[@mystic24100]

This is a very good explanation, wish I would have saw it 6 months ago. I like (not really) the ones that sometimes it works and sometimes not? Had the neighbors lawn mower that would not crank, no click, nothing. Bypass the switch and it worked. Never saw this before, but put in a new switch and it works every time. He comes over to pick it up and does not work!! Turn the switch on a couple more times and it works like a champ. He has used this summer, sometimes, he does have another mower. With all the safety switches there are a lot of connections to check, but once you understand the system you can find the problem.

[@CWellman9345]

Best explanation I have found! Great Job

[@blisteredthumbsdeas]

Great vid. Clean, precise and most importantly correct

[@hydrationtekirrigation1451]

thank you for the light in the darkness! now I know how to use ohm readings not just for zero resistance but for voltage loss, and I understand the circuit! nice.

[@JustinMillerAutomotive]

Glad it was helpful!

[@megamac3898]

Thank you very much for the clear Info I have spent ages on web to understand it till I saw ur videos , greetings from Egypt .

[@ifixeditmyself1926]

This was very helpful. I'm trying to figure out the click coming from my 99 Buick century at the solenoid on the starter and this helped me to understand the starter motor a lot better. Excellent!

[@labradormcgraw]

Neat mock-up. Makes it really easy to understand.

[@drjimjam1112]

Love the way this is made so simple. 4 places to check for voltage drop in the starter circuit.

[@MMGJ10]

Awesome video. This explains everything perfectly. Thank you!

[@funnyture]

most and best lesson I had from you tube. thanks for efforts sir.

[@mengluo4287]

wa, mind blowing! Best video on starter circuit on KZbin!

[@brentonpacker3291]

This is an amazing video. You must be an engineer. I love engineers!

[@aeriksh6873]

These Are the details I was looking for! Awesome and thanks

[@mikeamidi522]

Really Really wonderful demonstration. I really liked this demo.

[@radfourrunner8840]

Hi Justin, Thanks for this Excellent Setup and Presentation. Love your channel! One observation however... The starter relay (black module) is there so the ignition switch would not have to carry the current necessary to energize the starter solenoid (I measured 12 amps on my Toyota 4Runner). The starter relay is added to the system, so the ignition switch "start" contacts will only have to carry the low current needed to energize the starter Relay while the Relay contacts will carry the higher current needed to energize the starter solenoid (12 amps on my 1986 Toyota 4Runner). However, on your circuit the starter relay load supply is still taken from the ignition switch. This means that when ignition switch is in "start" position the current passing through the ignition switch "start" contact is: Low current to energize the starter Relay coil PLUS the approx. 12 amps needed to energize the starter Solenoid. This defeats the purpose of having the starter relay. This oversight is the cause of cranking problems on many first-generation Toyota 4Runners, and possibly other vehicles as well. Cheers! :)

[@tubetime39]

I was wondering about that relay and what it's purpose was. The relay doesn't carry the current to the starter Solenoid though,..eh? The wire from the relay carry's to the solenoid carries the current. Too bad he couldn't find where the problem was. He didn't explain that fuse or whatever between the pos batt cable going to the starter. Hmm. Confusing. Didn't explain touching meter from pos to pos either. Not the place for me to start learning car electrical. Bummer. i suppose I'll have to go through a lot more video's. Whew I wish one channel would go through from one step to the next. I can't even find a good book on it.

[@tubetime39]

PS, Nice board though 😊

[@christopherhuffer8925]

Trying to diagnose my 62 Impala. This video was really helpful!

[@sandyande]

Explained well, many thanks, sandy

[@todddra]

Great video. I'd like to see the troubleshooting continue to find the exact problem!

[@MagicNomadic]

was thinking the same thing, 2 years after your comment.....lol.

[@pablogomez7519]

same here because that's my problem 🙄 I turn the key to the run position and no power on the wire to the S terminal

[@donaldlucas8688]

Very cool setup. Well thought out!

[@acampbell198]

Great video, first time I am learning about voltage drop testing...love that!

[@jameslancaster8391]

Thank you for a great demonstration.

[@flightofthefatman]

Thanks for the up...really great demonstration.

[@benjamin-rw8qm]

best explanation I found online! thank you very much!

[@joelarbo3425]

This was an awesome teaching video!

[@gustavogarcia8214]

this is a very good. explanation about how the starter work and the possible problem we can have with.and how to check it

[@liraziyad5806]

Thank you. very simple and clear.

[@slugg6632]

Thank you for this clear video can’t wait to troubleshoot my sisters car

[@waiting4aliens]

Thank you. Very clear, and reinforced other knowledge gained.

[@jorgecabrera2589]

Excellent 👍 video , instructional, Sr,you teaching in school, you excellent how teaching, so good

[@Matthew-jr1xr]

Awesome video...saved me from buying a new battery.

[@dbayboyds409]

Fantastic. Thank you!

[@billsmith2212]

You did test between the battery POST and TERMINAL . Always try to go directly on the post if possible or be sure there isn't an excessive drop there . Always go directly on a starter battery post or solenoid post and not a tab or nut . There could be corrosion there . Great lesson .

[@nickayivor8432]

Good Evening Justin Miller take care and have a great day Justin Miller God bless you Justin Miller Great tutorial ❤ IT 👍 From Nick Ayivor from London England UK 🇬🇧

[@markferraro5250]

Great video Justin thank you

[@paultomasi4619]

Excellent! Very clear

[@mannyvalero3250]

Omg 🤯 it makes sense now. I can't thank you enough....😭

[@beefcakes27]

Excellent video, Justin..!

[@WTFisupDennys]

Frick this is seriously the best video!

[@nealk6387]

Buy a esi starter buddy. This tool has saved me a ton of time.

[@gasousman]

Wonderful vid. Thanks so much.

[@peterjuhasz5143]

Excellent vid, thank You very much!

[@superfluteman1]

Doesn't get better than this. Thanks

[@oriancunningham]

great presentation, highly informative

[@davidm3210]

Great video, thank you, If I'm not mistaken the first test determines if sufficient amperage is being delivered by the battery (when under load, of course). I seem to recall from Chris Fixx that a dip down to app. 9V (between battery terminals) is acceptable when cranking.

[@JustinMillerAutomotive]

That is correct. As a rule of thumb, when using a multimeter with min/max function, the voltage should not go below 9.6 volts during cranking. If using a lab scope, it should not go below 8.0 volts (because lab scopes are faster and capture the real minimum voltage).

[@tommyboyou812100]

@@JustinMillerAutomotive pop pop on

[@MrUnix-cu9yy]

This video is very informative. Thank you!

[@zeroalcohol]

Very good explanation. Thanks for sharing.

[@spelunkerd]

The main assumption you make when you use a device to put a load on a wire is that the device is drawing current. At 7:43, there wasn't enough energy flowing to fully close the solenoid contacts, so the main source of moving electrons comes through the relay to the S post, not through the big B+ wire. With no current on the B+wire, you haven't yet proven that wire is good, it was a failed drop test. On the other hand, if that wire was the problem we expect to see a drop. I really like your four step method, it's a way to quickly screen for wiring issues and get the job done without making a critical error. Doing it with a test light is a little faster but stands a chance of missing a problem because the light fails to detect an issue.

[@JustinMillerAutomotive]

You are right. In some cases, you may be trying to diagnose a starting system in which the starter isn't activating. While you will not be able to load the circuit without a working starter motor, you can still perform these steps to determine what the cause of the problem is. If the voltage is not dropping in the wires (even if the starter is not spinning), you can know that the wires are not the cause of the problem. Likewise, you can measure the voltage at the battery while attempting to crank the engine. Even if the starter does not spin, if the battery voltage remains high, then you can know that the battery is not the cause of the problem. It is true that you have not load tested the battery, but you can know that it is not the reason the starter is not turning on. You can load test it later, once you have found the problem with the starting system.

[@spelunkerd]

@@JustinMillerAutomotive This is first class teaching. One of the things that surprises me is how often working professionals mess this up. As much as thinking it through carefully is important, those guys need a streamlined four step check list approach, much like airline pilots use a checklist every time they get into a plane. Something that can be memorized, for a task done every day. Conventional teaching fails them because it isn't fast, there are too many options, too much thinking! ScannerDanner uses an easy four step test light algorithm, which gets a correct diagnosis about 90% of the time. The weakness is the insensitivity of the test light, especially for the final ground test.

[@rem6792]

Phenomenal video man

[@1977np]

Good beginner basics troubleshooting video. In some episode maybe you could outline starter problems specifically if all those 4 measurements are ok. Thx

[@timreeves3321]

HI Justin, great video! I'm hoping to make a board similar to yours for my high school auto class, and was wondering if you could give me some info on how you setup the back of the board?

[@iemandjwzz4614]

Absolutly great video!

[@grantdethlefs8820]

Great video!

[@Micscience]

I am a little confused when you did the (S) terminal test for the solenoid I think what you meant to say is you are missing like 2 volts and not 11 volts because the reading was 11 volts. Sorry I was just trying to make sense of what you are saying. By far you are the best at simplifying all this voltage drop so thanks for sharing.

[@JustinMillerAutomotive]

You are correct. I am not sure what I said, but that is definitely what I meant! There were about 2 volts missing at the "S" terminal compared to the positive battery terminal, which means that that those 2 volts are being dropped through some unwanted resistance somewhere between the battery and the "S" terminal.

[@hoanggia2222]

@@JustinMillerAutomotive Excuse me, I think that what you said in the video is right. You are missing 11,2 volts because the DVOM showed voltage between positive post(13,2 volts on the video) and "S" terminal, not the voltage at the "S" terminal. And the voltage at the "S" terminal is just about 2 volts compared to the negative post.

[@matssigm]

Thank you for a very good teaching. But i dont understand why the circuit still should read 12 volts when its closed ?

[@JoseGonzalas]

Excellent explanation. 10/10.

[@jamesutube33]

Great video, thank you.

[@jimbodee4043]

Great visual illustration of diagnosis

[@j.m.5995]

I like to place the ground wire on the actual case of the alternator to one of the mounting holes. That way it is primarily grounding itself thru that wire and not having to ground itself thru the block and anything that's grounded thru there. I avoid issues with magnetizing anything sensitive via the large inrush of initial current flow when you crank the engine

[@guitarplayerwannabee]

Fantastic tutorial. Many thanks

[@ifachner]

Great video, I'm trying to diagnose similar issues on a motorcycle. Any pointers? There is no relay not sure if the solenoid is grounded and the solenoid is separate.

[@seshachary5580]

very educative. Thank you regards

[@leonking9459]

wish we have this in our school, students will learn a lot more than written visual aids.

[@vicky-nc3to]

Porsche cayenne(tiptronic transmission) starts with ignition on + brake pedal pressed, so sometime if the engine starts without pressing brake, than is it the same problem of some safety switch in brake pedal as it is in clutch safety switch.... possibly short ?

[@alexander0194]

Thank you for this video. Immensely helpful.

[@nathandoering9115]

Hello Justin. I need to start off with saying this was a great video. Very informative. I was wondering if you could show the back side of the test station, how the faults are introduced, and what was used to create the faults. I would like to build this test station. Thank you!

[@EdWard-ji2hj]

Super useful and easy to understand. Thanks

[@creme757]

Excellent information, very helpful! BUT modern cars have Immobilizers which makes things quite a bit more complicating. Especially in European models

[@JustinMillerAutomotive]

Yes. The purpose of this procedure is to help you identify which branch of the circuit the problem is in. From there, you would need to do pinpoint tests to find out exactly what the cause is. These tests still work on modern cars with immobilizer systems. If you find that you are not getting the proper voltage to the "S" terminal, you would need to refer to a wiring diagram and determine how to narrow it down further. Often, a scan tool may will helpful.

[@milotorres6894]

Good explain techniques must've had a excellent teacher or degree or self taught either way much thanks for clearing the air had starer issues this helped the best by far good Man...

[@milotorres6894]

Spell check sucks .

[@Kmiler90]

What did you isolate to cause this issue? Ground?

[@kennidyulin2565]

Great video thanks for your knowledge

[@noniponipaa]

great video

[@splash5974]

Great video Justin! Question...I just bought a project boat. No crank, no click. Cleaned all cables, trickle charged the battery for a day, still no good. While testing continuity across some of the wiring, i noticed i have a direct path to ground at the "S" terminal, which is the trigger wire, and the large bolt opposite the "B" terminal. Which is the bolt leading into the starter motor. I remove all wires and wanted to very if it were bad wires or bad starter. The wires tested fine. I still have continuity from negative battery cable to the 2 terminals on the starter. Any ideas? Is this an internal short within the starter? Because the motor gets grounded through the case where it bolts to the block. Thank you kindly!

[@saginaw60]

Have seen this before. When ya put + power to the S terminal, the solenoid should click. On some starters they do not ground to case as Justin says, they ground through the armature. So examin the end of the communator to see if there is a black burned mark where the copper wires are soldered. May be necessary to change armature.

[@shrabhar]

Can this test be done by building a circuit with a embedded device to generate the cranking pulses

[@iriejam2164]

Excellent video! Concise, thorough. Could you say where I can get some teaching aids to purchase for my school?

[@871jamie]

My voltage drop issue on my 93 Z28 turned out to be in the starter itself. But turned out to be two bad starters. Had me scratching my head a while because two different starters had the exact same issue. Sometimes they worked and sometimes they just clicked. Off the car they worked fine but put them under a load and both did the same thing. Finally installed a remote starter to the starter with it in the car and had the same issue as using the ignition key. Bought an expensive starter and that fixed it.

[@JustinMillerAutomotive]

Starters come in all quality levels! I always recommend buying "100% new" starters, never remanufactured.

[@donaldlucas8688]

You should do a video of how you made this setup.

[@paulrobbins3362]

at 7:54 what scenario could exist where you would have a voltage reading, and what path would the current take

[@maximeabesque2426]

so clear thankyou

[@girlcanic]

What did you isolate to cause this problem?

[@jerryrobinson958]

This was a very good video

[@macknumber9]

Excellent video....is the 9.6 volts that the battery needs under load (when starting) the same on a lawn mower tractor or are the numbers a little different?

[@JustinMillerAutomotive]

In my opinion, if you have a 12-volt battery, 9.6 volts is a very good number to use, regardless of the application.

[@marvinhoodith7110]

Very great demo keep it up bro looking out for more.

[@summerrain3403]

This helped a lot, thank you for making this video.

[@BarlitosC]

Now to play around for 8 more hours seeing if it is an actual ground problem or the starter housing is just so corroded I can’t get a good read!!!

[@thugerrish]

Thumbs up for making that thing

[@CarlosGarcia-tv4rk]

Great video

[@RoamRight-ny6ho]

Great Video

[@Mazel_Tov_888]

I learned something.

[@Bartuz27]

thank you justin

[@johnnylrico]

What messes me up is Why is there battery voltage from the switch on the solenoid and positive terminal with everything off when there shouldn't be a ground?Why would that switch be grounded when the ignition is off?

[@annumlaz]

Excellent video to the point and easy to understand. Now, let's say the circuit components to the starter passed the voltage drop test, battery, battery positive, battery negative (ground), starter positive and solenoid positive(power). The solenoid grounds internally and provides power to the starter but the stater does not come on. Can you now do a voltage drop test on the starter to see if it has excessive internal resistance , missing volts, causing the starter's failed operation. Where would you put the leads of the DVOM on the starter and how would the readings look on the DVOM pass and fail?

[@JustinMillerAutomotive]

If you measure the voltage drop directly between the "M" terminal and the motor housing, you are measuring the voltage directly available to the motor. If your voltage is above about 9.6 volts, but the motor is not spinning, you have a problem with your motor. Most likely, the brushes are worn and need to be replaced, but it could also be an open or short in the armature windings.